Substrate processing apparatus having electrostatic chuck and substrate processing method

ABSTRACT

Examples of a substrate processing apparatus includes a chamber, an upper cover provided inside the chamber, an electrostatic chuck which includes an annular portion of a dielectric body and an embedded electrode embedded into the annular portion, the electrostatic chuck being provided inside the chamber, and a plasma unit configured to generate plasma in a region below the upper cover and the electrostatic chuck, wherein the annular portion includes an annular first upper surface located immediately below the upper cover, and a second upper surface located immediately below the upper cover and surrounding the first upper surface, the second upper surface having a height higher than a height of the first upper surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Application No. 62/942,660, filed on Dec. 2, 2019 in the United States Patent and Trademark Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

Examples are described which relate to a substrate processing apparatus and a substrate processing method.

BACKGROUND

U.S. Pat. No. 9,881,788 B discloses a method and an apparatus for depositing a stress compensation layer and a sacrifice layer on one of a front surface and a back surface of a substrate. Specifically, back side deposition is performed in a state where a front surface of a wafer is oriented upward. Such deposition of a layer on the front surface or the back surface can be executed to reduce stress to be introduced by deposition of a wafer on the front surface. The back side deposition may be executed to minimize a problem relating to back side particles generated during post-processing of deposition such as photolithography. Improvement of such a technique has been desired.

SUMMARY

Some examples described herein may address the above-described problems. Some examples described herein may provide a substrate processing apparatus and a substrate processing method which enable plasma processing to be performed on a lower surface of a substrate.

In some examples, a substrate processing apparatus includes a chamber, an upper cover provided inside the chamber, an electrostatic chuck which includes an annular portion of a dielectric body and an embedded electrode embedded into the annular portion, the electrostatic chuck being provided inside the chamber, and a plasma unit configured to generate plasma in a region below the upper cover and the electrostatic chuck, wherein the annular portion includes an annular first upper surface located immediately below the upper cover, and a second upper surface located immediately below the upper cover and surrounding the first upper surface, the second upper surface having a height higher than a height of the first upper surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a configuration example of a substrate processing apparatus;

FIG. 2 is a plan view of an electrostatic chuck;

FIG. 3 is a sectional view illustrating that a rotating arm is rotated;

FIG. 4 is a plan view illustrating a configuration example of the rotating arm;

FIG. 5 is a plan view of the rotating arm and the electrostatic chuck;

FIG. 6 is a sectional view illustrating introduction of a substrate;

FIG. 7 is a sectional view illustrating contact between the substrate and the electrostatic chuck;

FIG. 8 is a plan view of the substrate supported by the electrostatic chuck;

FIG. 9 is a sectional view illustrating an example of plasma processing;

FIG. 10A is a sectional view illustrating a configuration example of a substrate processing apparatus according to another example;

FIG. 10B is an enlarged view of a portion in FIG. 10A;

FIG. 11 is a sectional view illustrating a configuration example of a substrate processing apparatus including a microwave plasma generating apparatus;

FIG. 12 is a sectional view illustrating a configuration example of a substrate processing apparatus including an inductively coupled plasma apparatus; and

FIG. 13 is a sectional view illustrating another configuration example of the substrate processing apparatus including the inductively coupled plasma apparatus.

DETAILED DESCRIPTION

A substrate processing apparatus and a substrate processing method will be described with reference to the drawings. There is a case where the same reference numerals are assigned to the same or corresponding components, and repetition of description is omitted.

FIG. 1 is a sectional view illustrating a configuration example of a substrate processing apparatus according to an embodiment. This substrate processing apparatus is a parallel plate type plasma processing apparatus. A door 12 is attached to a chamber 10 so as to be able to provide a substrate to inside of the chamber 10 or take out a substrate from the chamber 10. The chamber 10 can be provided as part of a Dual Chamber Module (DCM) or part of a Quad Chamber Module (QCM). An upper cover 14 is provided inside the chamber 10. According to an example, the upper cover 14 is provided as a ground electrode. The ground electrode is an electrode for grounding.

The upper cover 14 includes a shaft portion 14 a and a disk portion 14 b connected to the shaft portion 14 a. The shaft portion 14 a is fixed at a first lifting mechanism 16 which can move in a z positive-negative direction, and can move in the z positive-negative direction. According to an example, the first lifting mechanism 16 is provided by a plate 16 a fixed at the shaft portion 14 a being fixed at an upper end of a bellows 16 b, and a plate 16 c fixed at the chamber 10 being fixed at a lower end of the bellows 16 b. As the first lifting mechanism 16, various configurations which move the upper cover 14 up and down inside the chamber 10 can be employed.

The disk portion 14 b has a circular shape or a substantially circular shape in planar view. A lower surface of the disk portion 14 b which is a lower surface of the upper cover 14 has, for example, a first lower surface 14 c, and a second lower surface 14 d which surrounds the first lower surface 14 c and which is located below the first lower surface 14 c. Therefore, the lower surface of the disk portion 14 b has a shape having a dent at the center.

The upper cover 14 which is a ground electrode, functions as an upper electrode having a parallel plate structure. To enable plasma coupling and prevent or reduce electric discharge, a difference in height between the first lower surface 14 c and the second lower surface 14 d can be made, for example, equal to or less than 1 mm.

An electrostatic chuck 20 is provided inside the chamber 10. The electrostatic chuck 20 includes a support body 20 a, an annular portion 20 b connected to a lower end of the support body 20 a, and an embedded electrode 20 c embedded into the support body 20 a and the annular portion 20 b. The support body 20 a is fixed at a second lifting mechanism 22. The second lifting mechanism 22 is configured to move the electrostatic chuck 20 up and down inside the chamber 10. According to an example, the second lifting mechanism 22 is provided by a plate 22 a fixed at the support body 20 a being fixed at the upper end of the bellows 22 b, and a plate 22 c fixed at the chamber 10 being fixed at the lower end of the bellows 22 b. As the second lifting mechanism 22, various configurations which move the electrostatic chuck 20 up and down inside the chamber 10 can be employed.

The support body 20 a and the annular portion 20 b can be formed with, for example, a dielectric body. The annular portion 20 b has an annular shape in planar view. The annular portion 20 b includes an annular first upper surface 20 d located immediately below the upper cover 14 and a second upper surface 20 e which is located immediately below the upper cover 14 and which surrounds the first upper surface 20 d. A height of the second upper surface 20 e is higher than a height of the first upper surface 20 d. A difference in height between the first upper surface 20 d and the second upper surface 20 e is, for example, greater than a thickness of the substrate to be processed.

FIG. 2 is a plan view of the electrostatic chuck 20. The annular portion 20 b is formed in a circular shape or a substantially circular shape. The first upper surface 20 d provides an annular surface, and the second upper surface 20 e provides an annular surface surrounding the first upper surface 20 d. A dashed line in FIG. 2 indicates the embedded electrode 20 c. The embedded electrode 20 c is embedded into the support body 20 a and the annular portion 20 b. When a positive or negative voltage is applied to the embedded electrode 20 c from an external power supply, dielectric polarization occurs at the annular portion 20 b which is a dielectric body.

FIG. 1 illustrates that the embedded electrode 20 c is located immediately below the first upper surface 20 d. Therefore, when a voltage is applied to the embedded electrode 20 c, the first upper surface 20 d and its vicinity dielectrically polarize. When a substrate which easily polarizes, such as a silicon substrate, is put on the first upper surface 20 d while charged in this manner, attractive force is generated due to clone force at the annular portion 20 b and the substrate, so that the substrate can be retained by the annular portion 20 b. Because the substrate is retained by the annular portion 20 b, it is not necessary to cause the support body 20 a to dielectrically polarize. Therefore, for example, it is possible to provide a ceramic tube as the support body 20 a and pass the embedded electrode 20 c through the ceramic tube.

FIG. 1 illustrates a rotating arm 30 located in the vicinity of an inner wall of the chamber 10. The rotating arm 30 is provided to transfer the substrate to inside of four chambers which constitute, for example, the QCM.

The substrate processing apparatus includes a plasma unit which is configured to generate plasma in a region below the upper cover 14 and the electrostatic chuck 20. According to an example, it is sufficient when plasma can be provided immediately below a region surrounded by the annular portion 20 b. In the example in FIG. 1, the plasma unit includes a shower plate 34, gas sources 41 and 42 and an RF power supply 43. The shower plate 34 is provided below the upper cover 14 so as to face the upper cover 14. The shower plate 34 includes plates 36 and 40 which have slits for providing gas in a z positive direction from the gas sources 41 and 42, and a spacer 38 provided between the plates. The whole of the shower plate 34 can be formed with a metal. According to another example, at least the plate 40 is formed with a metal. The gas sources 41 and 42 provide gas necessary for plasma processing. The RF power supply 43 provides high-frequency power for putting gas into a plasma state, to the shower plate 34.

In this manner, the substrate processing apparatus can perform plasma processing with a parallel plate structure including the upper cover 14 and the shower plate 34.

An example of a substrate processing method using this substrate processing apparatus will be described. FIG. 3 is a sectional view of the substrate processing apparatus immediately before the substrate is transferred to inside of the chamber. As illustrated in FIG. 3, the upper cover 14 is evacuated upward by, for example, a motor 50 moving the first lifting mechanism 16. Further, the electrostatic chuck 20 is evacuated upward by, for example, a motor 52 moving the second lifting mechanism 22.

Thereafter, a support pin which is part of the rotating arm is provided to a substrate receiving position inside the chamber 10 by the rotating arm 30 rotating. FIG. 4 is a plan view illustrating a configuration example of the rotating arm 30. In this example, a QCM having four chambers is provided. Support pins 30 a, 30 b and 30 c for supporting the substrate are provided to one of the four chambers 10 by the rotating arm 30 rotating.

FIG. 5 is a plan view of the support pins 30 a, 30 b and 30 c and the electrostatic chuck 20. The support pins 30 a, 30 b and 30 c are disposed at positions surrounded by the annular portion 20 b, of the electrostatic chuck 20.

Then, after the electrostatic chuck 20 is moved downward, and the annular portion 20 b is located below upper ends of the support pins 30 a, 30 b and 30 c, the substrate is put on the support pins 30 a, 30 b and 30 c provided immediately below the upper cover 14. FIG. 6 is a view illustrating that the substrate 54 is put on the support pins 30 a, 30 b and 30 c. For example, an external arm which supports the substrate 54 provides the substrate 54 on the support pins 30 a, 30 b and 30 c through the door 12. The substrate 54 includes an upper surface 54 a and a lower surface 54 b. The substrate 54 is, for example, a wafer formed with silicon or a wide bandgap semiconductor.

Then, the annular first upper surface 20 d is brought into contact with an outer edge portion of a lower surface of the substrate 54 by the annular portion 20 b being moved upward. FIG. 7 is a view illustrating a state where the first upper surface 20 d comes into contact with the outer edge portion of the lower surface 54 b of the substrate 54. In the process of the annular portion 20 b moving to a position above upper ends of the support pins 30 a, 30 b and 30 c, the support pins 30 a, 30 b and 30 c are separated from the substrate 54, and a central portion of the lower surface of the substrate 54 is exposed as the first upper surface 20 d supports the outer edge portion of the lower surface of the substrate 54. Thereafter, the support pins are evacuated from positions immediately below the upper cover 14 by the rotating arm 30 rotating.

FIG. 8 is a plan view of the electrostatic chuck 20 and the substrate 54 in FIG. 7. In FIG. 8, as a result of the substrate 54 contacting the first upper surface 20 d, the whole or the most portion of the first upper surface 20 d cannot be viewed in planar view, and the second upper surface 20 e appears. An inner edge of the first upper surface 20 d is indicated with a dashed line.

Then, the second upper surface 20 e is brought into close contact with the upper cover 14 while contact between the upper cover 14 and the substrate 54 is avoided. FIG. 9 illustrates that the second upper surface 20 e of the electrostatic chuck 20 is brought into close contact with the second lower surface 14 d of the upper cover 14. In this example, the second upper surface 20 e is brought into close contact with the second lower surface 14 d by the upper cover 14 being moved downward. According to an example, it is possible to prevent contact between the upper cover 14 and the substrate 54 by providing the first lower surface 14 c located above the second lower surface 14 d at the upper cover 14.

The second upper surface 20 e is located immediately below the second lower surface 14 d, and, when the second lower surface 14 d comes into contact with the second upper surface 20 e, flow of gas through space between the upper cover 14 and the electrostatic chuck 20 is inhibited. In another example, in a case where a lower surface of the disk portion 14 b of the upper cover 14 is made flat, as a result of the lower surface of the upper cover contacting the second upper surface 20 e, flow of gas through space between the lower surface of the upper cover and the second upper surface 20 e is inhibited. Further, the whole of the outer edge portion of the lower surface 54 b of the substrate 54 is attracted to the first upper surface 20 d by the electrostatic chuck 20.

According to an example, in a state illustrated in FIG. 9, space surrounded by the substrate 54, the electrostatic chuck 20 and the upper cover 14 becomes enclosed space. In this case, gas supplied from the gas sources 41 and 42 and plasma provided between parallel plates are not virtually provided to the enclosed space.

Then, plasma processing is performed on the lower surface 54 b of the substrate 54. Specifically, in a state where the substrate 54 is attracted to the first upper surface 20 d by the electrostatic chuck 20, plasma processing is performed on the central portion of the lower surface of the substrate 54 using the above-mentioned plasma unit. According to an example, significant plasma processing on the upper surface 54 a of the substrate 54 is prevented by making space surrounded by the substrate 54, the electrostatic chuck 20 and the upper cover 14 enclosed space during the plasma processing.

It can be said that a side of the upper surface 54 a of the substrate 54 is a device surface on which a device is formed. In this case, it is possible to protect the device by avoiding contact between the substrate 54 and the upper cover 14. It is possible to ensure this avoidance of contact by providing a concave portion illustrated in FIG. 1 on the lower surface of the upper cover 14.

As the plasma processing, it is possible to employ film formation, reformulation of a film formed on the substrate or etching. According to an example, in the plasma processing, an oxide film or a nitride film is formed at the central portion of the lower surface 54 b of the substrate 54. In this plasma processing, it is possible to form a film on the lower surface 54 b of the substrate 54 while suppressing film formation on the upper surface 54 a of the substrate 54. According to an example, the film formed at the central portion of the lower surface 54 b of the substrate 54 through the plasma processing alleviates warpage of the substrate 54.

In this manner, by causing the upper cover 14 to face the upper surface 54 a of the substrate 54 while the electrostatic chuck 20 holds the outer edge portion of the lower surface 54 b of the substrate 54, space above the upper surface 54 a of the substrate 54 is made enclosed space covered with the upper cover 14. It is possible to perform plasma processing on the central portion of the lower surface of the substrate 54 in a state where the substrate 54 is electrostatically attracted by the electrostatic chuck 20. Note that whether or not the substrate 54 is retained by the electrostatic chuck 20 can be switched at an arbitrary timing.

FIG. 10A is a sectional view of a substrate processing apparatus according to another example. FIG. 10A shows a cross-sectional view of a simplified version of an apparatus 400 capable of depositing on the back side of a wafer 451 (wafer 451 is shown as a black horizontal line in FIG. 10A). FIG. 10B shows a close up view of a portion of the apparatus 400. In particular, FIG. 10B illustrates how the wafer 451 is supported in the apparatus 400. The wafer 451 is supported at or near its periphery by a wafer support ring 453. The support ring 453 may contact the wafer 451 on the wafer's bottom surface, near the wafer edge in a region referred to as the support contact region. The support contact region is annularly shaped, and may be very small such that substantially the entire back side of the wafer (e.g., at least about 95%, or at least about 99%, as measured by surface area) is exposed during deposition. In some embodiments, the support contact region on the bottom of a wafer extends from the edge of the wafer inwards by about 5 mm or less, for example by about 1 mm or less. In the example of FIG. 10B, the support contact region is on the bottom of wafer 451, extending inwards from the periphery of the wafer by distance 461. The support ring 453 may also contact the top side of a wafer near the wafer edge. In these cases, the support contact region extends to the top side of the wafer. In this embodiment, the support ring may have a local cross-section that is C-shaped (rather than L-shaped as shown in FIG. 10B), extending both under and over a portion of the wafer at its periphery. Where the support ring contacts the top side of a wafer, care should be taken to ensure that the support ring does not damage the front side of the wafer. Such care may include ensuring that the support ring only contacts the wafer front side in a small defined area (the support contact area), and not in an active area. In some embodiments, the support contact area on the top of the wafer extends radially inward from the edge of the wafer by no more than about 0.5 mm, or by no more than about 0.25 mm.

In some embodiments, the support ring may be replaced with another wafer support mechanism that supports the wafer at/near its periphery. One example is a series of three or more disconnected pegs that support the wafer at different locations around its edge. In some cases the pegs may wrap around the wafer to better secure it in place during processing. The pegs (or other support mechanisms) may contact the wafer within the support contact regions described above.

In any case, the mechanism for holding the substrate may be designed such that the front side of the wafer does not substantially contact any portion of the reactor. As used herein, this means that any contact between the front side of the wafer 451 and the wafer support mechanism 453 (e.g., support ring, pegs, etc.) or other portion of the apparatus happens only near the edge of the wafer. The front side of the wafer includes an active region, where devices are fabricated, surrounded by a non-active peripheral region. The non-active peripheral region is present due to the geometry of the wafer and the need to handle the wafer during processing. By ensuring that the active region on the front side of the wafer does not contact any portion of the reactor, damage to the front side of the wafer may be minimized or avoided altogether. Contact that occurs at the very edge of the front side is not problematic in many cases, because the peripheral non-active region is typically removed and discarded when the substrate is cut into individual devices. As such, contact that happens in this region is not fatal to the final devices formed on the wafer.

Returning to the embodiment of FIGS. 10A and 10B, the support ring 453 holds the wafer 451 over the deposition region 459. The deposition region 459 is the area where reactant gases are introduced, reacted, and deposited on the wafer 451. The deposition region 459 is at least about coextensive with the area of the wafer 451. The bottom of the deposition region 459 may be defined by a lower surface 463, which in this embodiment also acts as a showerhead 463. The lower surface 463 is typically substantially parallel to the wafer 451. The height of the deposition region 459 (measured as the distance between the bottom side of the wafer 451 and the lower surface) may be relatively small in many cases. For example, the deposition region 459 may have a height between about 5-30 mm, for example between about 15-25 mm. In some embodiments, at least one of the lower electrode/showerhead surface 463 and support ring 453 is movable such that the height of the deposition region 459 may be tuned.

As mentioned, the lower surface 463 defines the bottom of the deposition region 459. In various implementations, the bottom surface 463 is powered (e.g., with an RF power source). In some embodiments, the lower surface 463 is adapted to act as a showerhead to provide process gases as needed. In other embodiments, the lower surface 463 may be simpler, and process gases may be provided through alternate inlets. Various different types of plasma may be used. For instance, the plasma may be generated directly in the deposition region 459 (i.e., a direct plasma) or may be generated at a different location and piped into the deposition region (i.e., a remote plasma). Any appropriate plasma generator may be used. In various embodiments the plasma is a capacitively coupled plasma generated between a powered lower electrode/showerhead 463 below the wafer 451 and a grounded upper electrode/top surface 455 above the wafer.

Above the wafer 451 is a small front side gap 457. This gap 457 extends between the top surface of the wafer 451 and an upper surface 455 in the reaction chamber. The size of the gap in FIG. 10A is exaggerated for the purpose of illustration. The upper surface 455 may be a heater, a ground plate, a chamber ceiling, or another type of plate/surface. In many cases this upper surface 455 acts as an electrode. In some embodiments, the height of the front side gap 457 is about 0.5 mm or smaller, for example about 0.35 mm or smaller. In these or other embodiments, the height of the front side gap 457 may be at least about 0.1 mm or bigger, for example at least about 0.25 mm or bigger. In many cases this upper surface 455 is substantially parallel to the wafer. This upper surface/electrode 455 may also extend around the edge of the substrate as shown in FIG. 10B such that it comes into contact with the wafer support ring 453. During deposition, inert gas (e.g., N2, Ar, etc.) is introduced from a front side inlet 465 and passes over the front side of the wafer 451. The front side inlet 465 may be positioned at or near the center of the wafer 451, such that the inert gas flows from the center of the wafer outward. This outward flowing inert gas helps ensure that no deposition-causing gases enter the front side gap 457 or come into contact with the front side of the wafer 451. In other words, the inert gas flow helps ensure that no material is able to deposit on the front side of the wafer 451 during back side deposition. To further protect the front side of the wafer 451, the front side gap 457 may be designed such that it is smaller than the thickness of the plasma sheath. This helps ensure that the plasma does not enter the front side gap where it could damage the substrate.

In many cases, the plasma is a capacitively coupled plasma that is generated between an upper electrode and a lower electrode. In certain cases the upper electrode may be connected with ground, and the lower electrode may connected with an RF source. The lower electrode may operate in part to collect electrons from the plasma. Dual RF (e.g., using and controlling both LF and HF frequencies and powers) may be used to modulate the stress of a deposited film in various cases.

In some embodiments, the back side deposition reactor is a bevel cleaning apparatus that has been modified to perform back side deposition. One example of a processing apparatus that may be modified is the Coronus® plasma bevel clean apparatus from Lam Research of Fremont, Calif. This apparatus is further discussed in the following U.S. patents, each of which is incorporated by reference in its entirety: U.S. Pat. No. 7,858,898, filed Jan. 26, 2007, and titled “BEVEL ETCHER WITH GAP CONTROL”; U.S. Pat. No. 7,943,007, filed Jan. 26, 2007, and titled “CONFIGURABLE BEVEL ETCHER”; and U.S. Pat. No. 8,562,750, filed Dec. 17, 2009, and titled “METHOD AND APPARATUS FOR PROCESSING BEVEL EDGE.”

Modifications useful for performing back side deposition typically include installation of a different wafer holder (e.g., an annular wafer holder that supports the wafer at its periphery and allows the back side of the wafer to remain exposed to plasma during processing), and installation of (or modification to) a different gas delivery system (e.g., to deliver deposition gases to the deposition region under the back side of the wafer, while also delivering inert gas to the front side gap above the front side of the wafer). Further, a heater and/or ground plate may be added above the wafer, if not already present.

As shown in FIGS. 10A and 10B, embedded electrode 453 a is embedded in the wafer support ring 453 so that the wafer support ring 453 can function as an electrostatic chuck as explained above. In some examples, the embedded electrode 453 a may be placed right below the wafer 451 to ensure electrostatic chuck function. In other words, the embedded electrode 453 a extends to the position right below the distance 461.

FIG. 11 is a sectional view of a substrate processing apparatus according to another example. In this example, as the plasma unit, a microwave plasma generating apparatus is provided. A plurality of rods 64 are provided inside the chamber 10. The rods 64 include a conductor 60 and a dielectric body 62 surrounding the conductor 60. A microwave is provided to inside of this dielectric body 62 from a coaxial waveguide. That is, the microwave fed from a microwave feeding portion of the coaxial waveguide ultimately reaches the plurality of rods 64. Then, microwave energy generates an electric field outside the dielectric body 62 of the rods 64, thereby plasma 70 is generated. In this manner, at the microwave plasma generating apparatus, plasma is generated at the plurality of rods 64. The substrate 54 can be electrostatically attracted to the first upper surface 20 d by the electrostatic chuck 20.

In a case where the microwave plasma generating apparatus is used, the upper cover 14 is not used as a parallel plate, and functions as a cover of the substrate 54. Therefore, it is possible to increase a difference in height between the first lower surface 14 c and the second lower surface 14 d to avoid contact between the substrate 54 and the upper cover 14. In other words, it is possible to provide a deep concave portion at the central portion of the lower surface of the upper cover 14. Further, while, in a case of a parallel plate, a distance from the substrate to the upper cover varies due to variation of warpage of the substrate 54, which can vary plasma density, such a problem does not occur by using the microwave plasma generating apparatus.

FIG. 12 is a sectional view of a substrate processing apparatus according to another example. In this example, as the plasma unit, an inductively coupled plasma apparatus is provided. The ICP reactor 120 can process substrates with high density plasma. Suitable ICP reactors include TCP™ systems from LAM Research Corp., Fremont, Calif. See also Ogle, U.S. Pat. No. 4,948,458 which is incorporated herein. The reactor includes a process chamber 121 in which plasma 122 is generated adjacent substrate 123. Upper cover 124 is provided above the substrate 123.

Temperature control of the substrate 124 is achieved by supplying helium gas through conduit 125 to a space between the substrate and the upper cover 124. The upper cover 124 can comprise an anodized aluminum electrode, which may be heated, or a ceramic material having a buried electrode therein, the upper cover 124 being powered by an RF source 126 and associated circuitry 127 for providing RF matching, etc. The temperature of the substrate 123 during processing thereof is monitored by temperature monitoring equipment 128 attached to temperature probe 129.

In order to provide a vacuum in chamber 121, a turbo pump is connected to outlet port and a pressure control valve can be used to maintain the desired vacuum pressure. Process gases can be supplied into the chamber 121 by conduits 131, 132 which feed the reactant gases to gas distribution rings extending around the dielectric window 133 or the process gases can be supplied through a dielectric showerhead window.

An external ICP coil 134 located outside the chamber in the vicinity of the window is supplied with RF power by RF source 135 and associated circuitry 136 for impedance matching, etc.

As is apparent, the external induction coil 134 is substantially planar and generally comprises a single conductive element formed into a planar spiral or a series of concentric rings. The planar configuration allows the coil to be readily scaled-up by employing a longer conductive element to increase the coil diameter and therefore accommodate larger substrates or multiple coil arrangements could be used to generate a uniform plasma over a wide area. When a substrate is processed in the chamber, the RF source 135 supplies the coil 134 with RF current preferably at a range of about 100 kHz-27 MHz, and more preferably at 13.56 MHz and the RF source 126 supplies the cover 124 with RF current preferably at a range of about 100 kHz-27 MHz, and more preferably at 400 kHz, 4 MHz or 13.56 MHz. A large DC sheath voltage below the surface of a substrate can be provided by supplying RF power to the electrode.

RF bias is applied to the substrate to generate ion bombardment of the growing film during the gap filling step. The RF frequency can be anything above the value necessary to sustain a steady state sheath, which is a few hundred kHz. Substrate bias has numerous beneficial effects on film properties, and can also be used to simultaneously sputter the growing film in the gap-fill step. This allows narrow, high aspect ratio gaps to be rapidly filled with high quality dielectric. RF bias can be used during the cap layer deposition step.

ICP Reactor 120 can be used to carry out the gap filling process of the invention wherein a heavy noble gas is used to increase the etch-to-deposition rate ratio (EDR) for void-free filling of sub 0.5 . mu.m high aspect ratio gaps. Gap filling processes are further described in copending application Ser. No. 08/623,825 filed on Mar. 29, 1996 entitled “IMPROVED METHOD OF HIGH DENSITY PLASMA CVD GAP-FILLING,” which application is incorporated herein.

At the substrate processing apparatus in FIG. 12, the above-mentioned electrostatic chuck 20 is provided. The electrostatic chuck 20 is provided to electrostatically attract an outer edge portion of a lower surface of the substrate 123. The substrate 123 is held by the electrostatic chuck 20, and plasma processing such as, for example, film formation, is performed on the lower surface of the substrate 123.

FIG. 13 is a sectional view of a substrate processing apparatus according to another example. While the apparatus in FIG. 13 is similar to the apparatus in FIG. 12, the apparatus in FIG. 13 is different from the apparatus in FIG. 12 in a configuration where the upper cover 124 comes into contact with the second upper surface 20 e. Providing enclosed space by the substrate 123, the electrostatic chuck 20 and the upper cover 124 on a side of the upper surface of the substrate 123 contributes to suppression of plasma processing on the upper surface of the substrate 123. 

1. A substrate processing apparatus comprising: a chamber; an upper cover provided inside the chamber; an electrostatic chuck which includes an annular portion of a dielectric body and an embedded electrode embedded into the annular portion, the electrostatic chuck being provided inside the chamber; and a plasma unit configured to generate plasma in a region below the upper cover and the electrostatic chuck, wherein the annular portion includes an annular first upper surface located immediately below the upper cover, and a second upper surface located immediately below the upper cover and surrounding the first upper surface, the second upper surface having a height higher than a height of the first upper surface.
 2. The substrate processing apparatus according to claim 1, wherein the plasma unit includes a shower plate provided below the upper cover so as to face the upper cover.
 3. The substrate processing apparatus according to claim 2, wherein the upper cover is provided as a ground electrode.
 4. The substrate processing apparatus according to claim 1, wherein the plasma unit includes a microwave plasma generating apparatus.
 5. The substrate processing apparatus according to claim 1, wherein the plasma unit includes an inductively coupled plasma apparatus.
 6. The substrate processing apparatus according to claim 1, wherein a lower surface of the upper cover includes a first lower surface and a second lower surface which surrounds the first lower surface and is located below the first lower surface.
 7. The substrate processing apparatus according to claim 6, wherein the second upper surface is located immediately below the second lower surface, and, when the second lower surface comes into contact with the second upper surface, flow of gas through space between the upper cover and the electrostatic chuck is inhibited.
 8. The substrate processing apparatus according to claim 1, wherein, when the lower surface of the upper cover comes into contact with the second upper surface, flow of gas through space between the lower surface of the upper cover and the second upper surface is inhibited.
 9. The substrate processing apparatus according to claim 1, comprising: a first lifting mechanism configured to move the upper cover up and down inside the chamber; and a second lifting mechanism configured to move the electrostatic chuck up and down inside the chamber.
 10. The substrate processing apparatus according to claim 1, wherein the embedded electrode is located immediately below the first upper surface.
 11. The substrate processing apparatus according to claim 1, wherein a support pin is provided so as to be able to be evacuated from a position immediately below the upper cover.
 12. A substrate processing method comprising in this order: putting a substrate on a support pin provided immediately below an upper cover; exposing a central portion of a lower surface of the substrate while supporting an outer edge portion of the lower surface of the substrate with an annular first upper surface of an electrostatic chuck; bringing a second upper surface of the electrostatic chuck into close contact with the upper cover while avoiding contact between the upper cover and the substrate, the second upper surface surrounding the first upper surface and having a height higher than a height of the first upper surface; and performing plasma processing on the central portion of the lower surface of the substrate in a state where the substrate is attracted to the first upper surface by the electrostatic chuck.
 13. The substrate processing method according to claim 12, wherein enclosed space surrounded by the substrate, the electrostatic chuck and the upper cover is created during the plasma processing.
 14. The substrate processing method according to claim 12, wherein a whole of the outer edge portion of the lower surface of the substrate is attracted to the first upper surface by the electrostatic chuck.
 15. The substrate processing method according to claim 12, wherein an oxide film or a nitride film is formed at the central portion of the lower surface of the substrate in the plasma processing.
 16. A substrate processing method comprising: making space above an upper surface of a substrate enclosed space covered with an upper cover by causing the upper surface of the substrate to face the upper cover while holding an outer edge portion of a lower surface of the substrate with an electrostatic chuck; and performing plasma processing on a central portion of the lower surface of the substrate in a state where the substrate is electrostatically attracted by the electrostatic chuck.
 17. The substrate processing method according to claim 16, wherein, in the plasma processing, a film is formed on the lower surface of the substrate while film formation on the upper surface of the substrate is suppressed.
 18. The substrate processing method according to claim 17, wherein warpage of the substrate is alleviated by the plasma processing. 